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Caption

Pacemaker. Coloured X-ray of a heart pacemaker implanted in a patient's chest. The pacemaker is fitted over the ribs below the collarbone (upper left). A wire (yellow) runs from the battery unit (blue) and across the sternum to the heart (near lower right). Pacemakers supply electrical impulses to the heart to maintain a regular heartbeat. They correct a condition called heart block, in which the heart's natural pacemaker fails to work properly because of heart disease. The device fits just below the skin and allows the patient to lead a normal, active life.